Either you have Javascript disabled within your web browser settings or you are using an older version of your web browser that is not Javascript enabled.

Using Internet Explorer, to check if Javascript is enabled select tools from the main menu select internet options, select the security tab, then select internet under the zone selection area. Move the slider bar to medium. If you are using a custom security level then select the custom level button. From the security settings screen make sure that Active Scripting is enabled.

Using Netscape Navigator, to check if javascript is enabled select edit from the main menu then select preferences. From the preferences screen select advanced from the left selection area. From the advanced settings make sure that enable Javascript is selected.